The present invnetion relates to an Acheson furnace type silicon carbide whisker production apparatus.
Techniques for producing silicon carbide whisker useful as a composite reinforcement are broadly classified into a gas phase synthetic process and a solid phase synthetic process.
The gas phase synthetic process comprises thermally decomposing in a hydrogen gas stream, for example, a gaseous mixture of a silicon halide compound with a hydrocarbon, or carbon and a halogenated organosilicon compound.
In this gas phase synthetic process, however, since the halogenated compound used as the starting material is detrimental to health, the handling therof is attended with unfavorable danger.
In the solid phase synthetic process, a mixture of a powdery silicon source component with a carbon component is used as the starting material, while no halogenated compound is used as the starting material, so that the handling of the starting material is not attended with danger. Further, since the substance to be used as the starting material is available at a low cost, this process is currently practiced as an industrial production means.
Examples of the apparatus used for heating and reacting the above-described mixture as the starting material include an Acheson furnace type reactor (see, for example, Japanese patent application Kokai publications No. 48-93600 and No. 58-145700) and a tubular reactor provided with an electric heater or a high frequency induction heating means (see, for example, Japanese patent application Kokai publication No. 62-3099).
The Acheson furnace type reactor is an apparatus used for heating a plurality of reaction vessels packed with the starting material in a furnace. Therefore, in this apparatus, only batch production is possible and no continuous operation can be conducted. Further, in each reaction vessel packed with the starting material, it is difficult to uniformly heat the apparatus to a desired temperature.
In contrast, the tubular reactor wherein an electric heater is used as a heating source is an apparatus wherein the reaction vessels packed with the starting material are successively sent into the furnace so as to continuously produce silicon carbide whisker. Therefore, the mass productivity is superior to the batch-wise Acheson furnace type reactor.
The tubular reactor, however, gives rise to unfavorable phenomena during the operation, such as deterioration in the insulation of the heater, the burnout of the heater, and consumption of the heater to a minute extent. In each time, the operation should be stopped to repair the heater, so that normal operation is inhibited.
Further, when an improvement in the efficiency of uniform heating and an increase in the size of the equipment are intended in the electric heating tubular reactor, it is necessary to increase the number of heaters provided, which gives rise to an increase in the cost of the equipment and an unfavorable increase in the frequency of failure.